This invention relates to a method of vapor depositing a material onto a substrate.
In vapor depositing a material onto a substrate, it is often desired that the layer of deposited material be continuous without any cracks and also that the surface of the substrate remain relatively free of any impurities which might evaporate onto the surface during the vapor depositing process. Frequently, the surface of the substrate has one or more steps over which the material is to be vapor deposited. In order to effectively cover the substrate step with a continuous layer of material which is free of any cracks, the substrate is often heated to a higher temperature prior to vapor depositing the material.
In order to raise the temperature of the substrate, a heater must be used, such as a tungsten-filament radiant heater. Such a heater may be a source of impurities which can evaporate onto and contaminate the surface of the substrate. Such impurities are undesirable since they often diffuse into the substrate, in particular the insulating layers, and alter the electrical characteristics thereof.